Submerged booster pump assembly



p 4, 1956 J. F. D! STEFANO EIAL 2,761,393

SUBMERGED BOOSTER PUMP ASSEMBLY Filed May 19, 1950 2 Sheets-Sheet 1 Fig.1

1571/5 27ZLUT7 Jbim Eran/c DL'Sfefano Frederick E. Smilh sum/macro Boosrnn PUMP AssEsmLY John Frank Di Stefano, L mdhurst, and Frederick E.

Smith, Cleveland Heights, Qhio, assignors to Thompson Products, Inc., Cleveland, ()hio, a corporation of Ohio Application May 19, 1359, Serial No. 163,094

1% Claims. (Cl. ilk-38) This invention relates generally to a pump and motor unit adapted to be mounted on a wall of a tank or fuel cell in submerged relation to the fluid contained within the closure.

More specifically, the present invention relates to an improved structure whereby vapor removal features are incorporated in the pump structure to permit more efficient operation of the booster pump.

According to the general features of the present invention, a booster pump is provided which employs an impeller unit consisting of two individual and separate stages. The first stage of the unit includes a plurality of helices comprising a helicoidal axial flow stage which together with an impeller chamber defined by a pump housing operates to draw fluid from an inlet sump and advance such fluid axially toward the second stage of the pump.

The second stage of the impeller unit includes a plurality of radial blades which blend in with the vanes of the helicoidal stage and operate to pressurize fluid delivered by the helicoidal impeller through a centrifugal pumping action.

The impeller chamber is peripherally vented to permit egress of vapor-laden fuel outwardly from the impeller chamber in the locale near the peripheral edges of the helices.

A volute pumping chamber surrounds the radial blades of the second stage of the pump and is also vented in the locale of the center of the pumping chamber near the downstream end of the helicoidal impeller to permit egress of vapor-laden fuel from a low pressure area which exists near the center of the pumping chamber.

A vapor deflector is carried by the pump housing and operates to deflect ejected vapor-laden fuel into the tank away from the inlet sump.

The particular structural arrangement described herein is especially efi'icient because the first stage of the pump permits the fuel to be taken in at low velocities and in a shockless condition whereupon the fuel is gradually pressurized and delivered to the highly efiicient radial stage for subsequent delivery under increased pressures. It is thus possible to employ a smaller and higher speed impeller unit for meeting any specific combination of high altitude operating conditions.

The vapor-removal features of the structural arrangement herein described not only exploit the advantages inherent in removing vapor-laden fuel from the locale of the low pressure zone existing near the center of the pumping chamber, but in addition, exploits the recirculation fiow that exists in a helicoidal impeller so that vapor-laden fuel may be forced outwardly in the locale of the periphery of the helicoid.

It is an object of the present invention, therefore, to provide a novel booster pump adapted for submerged operation and having improved vapor-removal features.

Another object of the present invention is to provide a booster pump adapted for submerged operation which atent employs two distinct types of impeller stages whereby fuel may be gradually pressurized in the first stage and and ultimately delivered to greatly increased pressures after passing through the second stage.

Another object of the present invention is to provide a booster pump assembly adapted for submerged operation having a two-stage impeller unit whereby fuel may be taken in the first stage without experiencing a shock condition at the inlet of the pump.

A further object of the present invention is to provide a booster pump assembly adapted for submerged operation employing a two-stage impeller unit whereby smaller, higher speed impeller units may be successfully employed.

Yet another object of the present invention is to increase the altitude performance capacity of a booster pump impeller through the provision of vapor-removal features which exploit the re-circulation effect in a helicoidal axial flow pumping stage.

Many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description which follows and the accompanying drawings in which a preferred structural embodiment is shown incorporating principles of the present invention.

On the drawings:

Figure 1 is a broken cross sectional view with parts in elevation showing a booster pump assembly according to the present invention mounted for submerged operation in a fuel cell.

Figure 2 is a side elevational view with parts broken away and with parts shown in section of a booster pump assembly according to the present invention.

Figure 3 is an enlarged exploded view in elevation of a radial impeller and a helicoidal impeller employed in the combination impeller unit of the present invention.

Figure 4 is a bottom plan view of the radial impeller shown in Figure 3; and

Figure 5 is a top plan view of the radial impeller shown in Figure 3.

As shown on the drawings:

An electric motor pump unit it) adapted for submerged operation within a fuel cell 9 and constructed in accordance with the present invention includes an electric motor 11 mounted in firm assembly with a pump body or housing 12 which, in turn, is mounted on one wall of the fuel cell 9 in a conventional manner.

In the preferred embodiment shown, the pump housing 12 takes the form of an integral casting element which includes an open-ended casing divided into an inlet sump 13, an impeller chamber 14, a volute pumping chamber 16, a conicaliy-shaped enclosure area 17 adjacent the volute pumping chamber 16, and a reduced neck portion 13.

The reduced neck portion 18 of the housing 12 is provided with various bores and counterbores respectively receiving a bearing unit B, a flame trap T, and a seal S, the structural details of which are conventional in The other end thereof lies in registry with an aperture 23 formed in a cover member 24 attached to the pump housing 12, the aperture 23 being closed by a cap 26 carried on the head end of the bolt 27 threaded as at 28 in the apertured boss 29 of the conduit fitting 22.

The pump of the present invention actually embodies what might be identified as two distinct pumping stages and the impeller unit of the pump includes two specific types of impellers or impeller sections.

Referring first to Figures 2 and 3, a first helicoidal impeller indicated generally by the reference numeral 30 is shown as having a triple helix, the individual helices indicated by the reference characters 3%, 3% and 39c. The edges of the helices at the inlet end of the pump are preferably sharp knife edges 31.

The hub 3th! of helicoidal impeller 36 is secured on the drive shaft 19 to mount the impeller in the chamber 14 to draw in fluid from the inlet sump 13 and advance such fluid axially through the impeller chamber 14 along the general axis of the impeller 30. Because of the sharp slicing inlet characteristics of the knife edges 31, the fluid drawn in by the helicoidal impeller 30 will experience substantially no shock and will thereby preclude the creation of vapor-releasing disturbances at the inlet of the pump structure, a deficiency which is common to many other types of booster pumps adapted for installation on high altitude aircraft and featuring vaporremoval structures.

Referring now to Figures 2, 3, 4 and 5, a second impeller 32 is shown which comprises a radial impeller operable in the volute pumping chamber 16 to pressurize through a centrifugal pumping action the fluid delivered thereto by the helicoidal impeller 30.

As may be seen on the drawings, the radial impeller 32 includes a substantially generally circular disc body portion 33 which is centrally apertured to pass the drive shaft 19 through to the helicoidal impeller 30 and also has a hub 34 in the locale of the central aperture by which the radial impeller 32 may be drivingly connected to the drive shaft 19.

A plurality of spaced apart blades are provided on the bottom face of the disc 33, the blades being indicated by the reference characters 32a, 32b and 320, respectively. The edges of the blades 32a, 32b and 32c are constructed to define a helicoidal lead surface so that the radial impeller 32 may be closely assembled with the helicoidal impeller 30 in such a manner as to have the blades thereof blend into the trailing or downstream ends of the three helices 30a, 30b, 30c.

It will be understood that although fluid drawn in by the helicoidal impeller 30 will be gradually pressurized as it advances axially in the axial flow pumping stage, the greatest part of the pressure of the pump will be imparted to the fluid by the centrifugal pumping action of the radial blades. In this manner the two specifically diflerent impeller components are combined in an integral impeller unit in such a manner as to exploit the inherent good features of each. The helicoidal impeller 30 permits fuel to be taken in through a comparatively large inlet eye at low velocity and in a shockless condition for gradual pressurization and ultimate delivery to a pure radial pumping stage. Thus, a smaller, higher speed impeller unit may be employed without sacrificing efliciency characteristics.

To further increase the altitude performance capacity of the pump provided in accordance with the present invention, an improved vapor-removal arrangement has been provided.

It has been found that a low pressure zone exists near the hub diameter of the downstream end of the helicoidal impeller in the general locale of the central portion of the pump chamber 16. Since this low pressure zone fosters the accumulation of vapor-laden fuel, the disc 33 of the radial impeller 32 is provided with a plurality of spaced-apart vapor removal apertures. In the present embodiment three apertures identified by the reference numeral 36 and three apertures identified by the reference numeral 37 are provided on concentric circular axes in predetermined spaced relationship, the apertures 37 being of slightly larger area than the apertures 36.

Vapor-laden fuel may thus exit from the volute pumping chamber 16 through the apertures 36 and 37 and into the comically-shaped enclosure 17, whereupon the vaporladen fuel will pass outwardly through a plurality of spaced apertures 33 defined in the housing Walls. By forming each of the apertures 38 on an axis generally perpendicular to the side walls of the conically-shaped enclosure 17, the bore passages of the apertures 38 are actually slanted upwardly to direct the exiting fuel therefrom away from the lower portion of the pump housing.

A screen filter 39 may be attached to the pump housing to encircle the reduced neck portion 18 and the inlet to the sump 13 so that no pump damaging foreign particles can enter the pump.

The construction design of the impeller unit contemplates the provision of a helicoidal impeller 30 which has a screw displacement greater than the fluid delivery capacity of the pump. Moreover, the walls of the impeller chamber 14 are so related to the helicoidal impeller 30 as to aflord a rather coarse running clearance indicated generally by the reference numeral 40. It will be apparent, therefore, that a re-circulation flow will exist in the helices 30a, 34% and 300 of the helicoidal impeller 35].

According to the present invention we have exploited this characteristic in connection with a vapor-removal feature. A plurality of apertures 41 are provided in the side walls of the impeller chamber 14 defined by the housing 12. The re-circulation flow has the efiect of forcing vapor-laden fuel outwardly to the periphery of the helices 30a, 30b and 30c whereupon the vapor-laden fuel will escape through the coarse running clearances 40 and through the apertures 41.

A vapor deflector 42 having side walls 42a substantially encircling the impeller chamber 14 and pumping chamber 16 portion of the pump housing 12 is provided to direct the exiting vapor-laden fuel upwardly away from the inlet sump 13.

It will be noted that the vapor deflector 42 is further provided with a radially inwardly extending portion 42b which is axially flared to define an inlet eye 43 directly adjacent the knife edges 31 of the helicoidal impeller 30.

Although it is contemplated that various minor structural modifications may be made to the preferred embodiment herein described in considerable detail for the sake of clarity only, it should be clearly understood that we wish to embody within the scope of this patent all such modifications as reasonably and properly come within the scope of our contribution to the art.

We claim as our invention:

l. A pump adapted to be submerged in a liquid and deliver gas and vapor freed liquid which comprises a pump casing having a central impeller chamber with an inlet at one end and a pumping chamber surrounding the other end of the impeller chamber, a pump impeller comprising a central hub having a radially extending flange and radial pumping vanes depending from one side of said flange for rotation in said pumping chamber, helical vanes surrounding said hub to axially advance liquid from the inlet towards the pumping chamber and extending into the spaces between the radial pumping vanes, said flange having vapor escape ports formed therein, whereby liquid fluid is advanced axially and pumped centrifugally and vapor-laden fluid is vented outwardly through said vapor escape ports.

2. A pump impeller for a vapor separating pump which comprises a central hub, a radially extending flange on said hub, radial pumping vanes depending from one face of said flange, a plurality of helical vanes surrounding said hub and extending into the spaces between the radial pumping vanes, and vapor escape ports in said flange.

3. A pump impeller as defined in claim 2, each of said helical vanes having a leading edge formed in a knife edge and each helical vane forming a separate helical path around the hub, said vapor escape ports venting vapor laden fluid from the spaces between said helical vanes.

4. A pump adapted to be submerged in a liquid and deliver gas and vapor freed liquid which comprises a pump casing having a central impeller chamber with an inlet at one end and a pumping chamber surrounding the other end of the impeller chamber, a pump impeller comprising a central hub having a radially extending flange and radial pumping vanes depending from one side of said flange for rotation in said pumping chamber, helical vanes surrounding said hub to axially advance liquid from the inlet towards the pumping chamber and extending into the spaces between the radial pumping vanes, said flange having vapor escape ports therein, and said casing having vapor escape ports at the periphery of said helicoidal vanes, whereby liquid fluid is advanced axially and pumped centrifugally while vapor laden fluid is vented outwardly.

5. A pump and motor unit adapted to be mounted inside of a tank comprising a hollow pump housing substantially closed at one end and having an inlet sump formed therein communicating with the tank, an impeller chamber formed in said housing leading away from the inlet sump, a volute pumping chamber formed in sa1d housing at the end of said impeller chamber and said housing having a discharge outlet formed therein for sa1d impeller chamber, a reduced neck portion at the substantially closed end of said housing, a drive shaft ournalled for rotation in said reduced neck portion, a pump 1mpeller connected to said shaft comprising a central hub having a radially extending flange and radial pumplng vanes depending from one side of said flange for rotation in said dumping chamber, helical vanes surrounding said hub to axially advance liquid from the inlet to wards the pumping chamber and extending into the spaces between the radial pumping vanes, said flange having vapor escape ports formed therein, and said hOllSlllg having ports communicating therewith to carry vapors from near the center of the pumping chamber and near the central portion of the downstream end of the hehcoidal impeller to the outside of said housing.

6. A pump and motor unit as defined m cla1m 5, and means forming vapor escape apertures in sa1d housing extending from said impeller chamber near the periphery of said helicoidal impeller to the outside of sa1d housing.

7. In a motor driven pump of the type characterized by the combination of one rotatable impeller providing screw blades and a radial disk together forming serieshelicoidal-centrifugal stages, the improvement of a pump casing having cylindrical walls providing a coarse running clearance with the peripheral edges f S3.ld screw blades, the screw blades having a screw dlsplacement greater than the fluid delivery capacity of the pump, thereby effecting recirculation in the spaces between the screw blades, and vapor escape passages formed m sa1d cylindrical walls extending radially outwardly from oncumferentially adjacent said screw blades to the outs1de of the pump and venting vapor laden fluid forced radially outwardly by the recirculation flow.

8. A pump including a housing having a pumping chamber with an outlet and an impeller chamber coaxial therewith and adjacent thereto with an inlet, the walls of said impeller chamber being cylindrical, a longitudinally extending helicoidal impeller having helical screw vanes operable in the impeller chamber to draw fluid through the inlet at one end of the helicoidal impeller and advance the fluid axially towards the pumping chamber at the other end of the helicoidal impeller and having a coarse running clearance between said walls and the peripheral edges of said screw vanes, a radial impeller at the said other end of said helicoidal impeller operable in the pumping chamber to pressurize the fluid from the impeller chamber by a centrifugal pumping action, said screw vanes having a greater screw displacement than the delivery capacity of said radial impeller, thereby to provide recirculation in the helices of said screw vanes, and radially extending passage means formed in said housing circumferentially adjacent the periphery of said helical screw vanes of said helicoidal impeller effecting the escape of vapor laden fuel forced outwardly from said impeller chamber at the periphery of said helicoidal impeller by the recirculation flow.

9. A pump including a housing having a pumping chamber with an outlet and an impeller chamber coaxial therewith and adjacent thereto with an inlet, a lonitudinally extending helicoidal impeller having helical screw vanes operable in the impeller chamber to draw fluid through the inlet at one end of the helicoidal impeller and advance the fluid axially towards the pumping chamber at the other end of the helicoidal impeller, a radial impeller at said other end of said helicoidal impeller operable in the pumping chamber to pressurize the fluid from the impeller chamber by a centrifugal pumping action, and radially extending passage means formed in said housing circumferentially adjacent the periphery of said helical screw vanes of said helicoidal impeller effecting the escape of vapor laden fluid outwardly from said impeller chamber at the periphery of said helicoidal impeller, said radial impeller and said housing having vapor escape ports formed therein together providing a vapor escape passageway releasing vapor laden fuel from the spaces between the helical vanes at the said other end of said helicoidal impeller.

10. A pump including a housing having formed therein a coaxially aligned pumping chamber with an outlet and an impeller chamber with an inlet, a helicoidal impeller operable in the impeller chamber to draw fluid through the inlet and advance the fluid axially through the impeller chamber, a radial impeller operable in the pumping chamber to pressurize the fluid from the impeller chamber by a centrifugal pumping action, outwardly extending passageways formed in said housing for the escape of vapor laden fuel from the periphery of the helicoidal impeller, outwardly extending passageways formed in said radial impeller and in said housing for the escape of vapor laden fuel from the downstream end of the helicoidal impeller, and a vapor deflector carried by the pump housing adjacent said inlet deflecting the escaping vapor laden fuel away from the pump inlet.

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